Conventionally, for a separate refrigeration cycle apparatus (for example, a refrigerating and air-conditioning apparatus) in which an indoor unit and an outdoor unit are connected by a liquid extension pipe and a gas extension pipe, there is a technique that estimates a refrigerant-amount presence ratio in the refrigerating and air-conditioning apparatus with regard to the length of the liquid extension pipe by using information of, for example, a pressure sensor, a temperature sensor, and a liquid-level detection sensor required for operation of the refrigerating and air-conditioning apparatus, and detects leakage of the refrigerant based on the estimation result (for example, see Patent Literature 1).